Image Compression Approach for Encryption and Decryption using RGB Content with DCT Function

in this cryptosystem, we have considered RGB images for two-dimensional (2D) data security. Security of RGB images during transmission is a major concern, discussed globally. This paper proposes a novel technique for color image security by random cipher associated with 2D discrete cosine transform. Existing techniques have discussed the security of image data on the basis of the keys only (which provide only one layer of security for image data), but in the proposed cryptosystem, the keys and the arrangement of cipher parameters are imperative for correct decryption of color image data. Additionally, key multiplication side (pre or post) with The RGB image data should inevitably be known, to correctly decrypt the encrypted image data. So, the proposed cryptosystem provides three layers of security for RGB image data. A computer simulation on standard examples and results is given to support the fixture of the scheme. Security analysis and detailed comparison between formerly developed techniques and proposed cryptosystem are also discussed for the robustness of the technique. This method will have large potential usage in the digital RGB image processing and the security of image data. There are many image encryption schemes have been proposed, each one of them has its advantages and disadvantages. This paper presents practical approach on image encryption and decryption technique using matrix transformation. The proposed scheme is useful for encryption of large amounts of data, such as digital images. First, we use discrete cosine transformation to get a blocked image. Second, a pair of keys is given by using matrix transformation. Third, the image is encrypted using private key in its transformation domain. Finally the receiver uses the public key to decrypt the encrypted messages. This technique satisfies the characters of convenient realization, less computation complexity and good security. The salient features of the proposed image encryption method are loss-less, symmetric private key encryption, a very large number of secret keys, and key-dependent pixel value replacement.